your professor is the reviewer

not you. though you worked for your professor in the actual reviewing.
The point is, your professor's fame made the journal choose him as a reviewer, you don't have the fame, at least at that time. To be a reviewer is just a proof of being "famous" (though not necessarily) in a certain field, used as a judgement by INS. So, all in all, work for you professor can't prove you are acknowledged by the editors. Got it? Just like if you work for a NSF grant doesn't mean you have the ability to obtain the grant, you prof. has.